1. Field of the Invention
The present invention relates to a multi-frequency telescope apparatus for celestial observations using a reflecting telescope for observing celestial objects which emit radio waves, infrared rays and visible light, such as fixed stars, planets, galaxies, star clusters and gases.
2. Description of the Prior Art
FIG. 8 is a cross-sectional view of a conventional reflecting optical telescope apparatus of a Cassegrain optical system disclosed, for example, in Japanese Patent Application Laid-Open Gazette No. 05-19179. FIG. 9 is a sectional view of the optical system of the conventional telescope apparatus depicted in FIG. 8. Reference numeral 1 denotes radio waves from celestial objects; 2 denotes infrared and visible rays from the celestial objects; 3 denotes a main reflecting mirror coated over the entire area of its curved glass surface 3a with a thin metallic film 11 as of aluminum (Al); and 4 denotes a sub reflecting mirror coated over the entire area of its curved glass surface 4a with a thin metallic film 11 as of aluminum, for bringing the reflected light from the main reflecting mirror to a Cassegrain focus 6 where a light receiving element or an optical system 9 for an observation apparatus is placed.
The above is a typical example of an infrared, visible-light telescope. On the other hand, a conventional radiotelescope has its main and sub reflecting mirrors formed of aluminum, CFRP or similar conductive material instead of glass and employs a primary radiator for a receiver or beam transmission system in place of the light receiving element or optical system 9 for observation apparatus.
The operation of the prior art example of FIG. 8 will be described below.
The radio waves or infrared and visible rays 2 from celestial objects are reflected first by the main reflecting mirror 3, and reflected again by the sub reflecting mirror 4 placed before the focus of the main reflecting mirror 3 to form an image on the Cassegrain focus 6. And, celestial observations are made by the light receiving element or optical system 9 of the infrared, visible-light telescope, or the primary radiator or beam transmission system 5 of the radiotelescope disposed at the position of the Cassegrain focus 6.
As described above, the celestial observations are carried out receiving radio waves or infrared and visible rays from the celestial objects; the radio waves are emitted only from low-temperature portions of celestial objects, whereas the infrared and visible rays emanate only from high-temperature portions. With the conventional telescope apparatus of such a construction as referred to above, the celestial objects of locally different temperatures cannot be observed in their entirety at one time, and hence images obtained with dedicated telescopes corresponding to respective frequencies need to be pieced together to get the whole picture of what are observed. Moreover, observation frequencies of radiotelescopes have recently approached approximately {fraction (1/300)} of frequencies of the visible and infrared rays, and the precision required of the radiotelescopes has sharply been improved accordingly; hence, it is uneconomical to use telescopes corresponding to the respective frequencies.
It is therefore an object of the present invention to provide a multi-frequency telescope apparatus for astronomical observations that uses only one reflecting telescope capable of simultaneously receiving radio waves, infrared and invisible rays.
According to an aspect of the present invention, there is provided a multi-frequency telescope apparatus for celestial observations using a reflecting telescope which includes a first reflecting mirror coated over the entire area of its surface with a grid-like metallic film that reflects radio waves but permits the passage therethrough of infrared and invisible rays and coated over the entire area of its back with a fall-face metallic film that reflects the radio waves and the infrared and visible rays.
Preferably, according to another aspect of the present invention, the multi-frequency telescope apparatus further includes a second reflecting mirror coated over the entire area of its surface with a grid-like metallic film that reflects radio waves but permits the passage therethrough of infrared and invisible rays and coated over the entire area of its back with a full-face metallic film that reflects the radio waves and the infrared and visible rays.
Preferably, according to another aspect of the present invention, the second reflecting mirror is coated over the entire area of its surface with a full-face metallic film that reflects the radio waves and the infrared and visible rays.
Preferably, according to another aspect of the present invention, the multi-frequency telescope apparatus has a Cassegrain optical system in which the first reflecting mirror is a concave mirror and the second reflecting mirror is a convex mirror.
Preferably, according to another aspect of the present invention, the multi-frequency telescope apparatus has a Cassegrain optical system in which the first reflecting mirror is a convex mirror and the second reflecting mirror is a concave mirror.
Preferably, according to another aspect of the present invention, the multi-frequency telescope apparatus has a Gregorian optical system in which the first and second reflecting mirrors are both concave mirrors.
Preferably, according to another aspect of the present invention, the multi-frequency telescope apparatus has a prime focus optical system using only the first reflecting mirror.
Preferably, according to another aspect of the present invention, the multi-frequency telescope apparatus further includes a plane mirror placed upstream or short of the focal point of the radio waves on the optical axis of the first reflecting mirror, and a plane mirror placed upstream or short of the focal point of the infrared and visible rays on the optical axis of the first reflecting mirror.
Preferably, according to another aspect of the present invention, the multi-frequency telescope apparatus further includes observation equipment, such as a receiver and a camera, disposed at the focal points of the radio waves and the infrared and visible rays displaced from the optical axis of the main reflecting mirror.
Preferably, according to still another aspect of the present invention, the multi-frequency telescope apparatus is not limited specifically to the radio waves and the infrared and visible rays and is capable of simultaneous observations of two incident waves of different frequencies.